I don't know that we have enough information to answer your "How can I change this?" question yet.
The next question is, what is the format of the actual file that can't be changed? Is it also a .PDF? If not, then what is the file type?
You showed us a .PDF and say it can't be changed. If all you have is Adobe Reader or a Browser previewer, then you are right - a .PDF cannot be changed.
What are the permissions on the file? If the file is READ ONLY then again, you are right, it cannot be changed. However, if you own the file (in the computer security sense of "own") then you should be able to work with it by changing the file permissions - if that was the problem.
It is possible to protect an Excel file from being changed without resorting to file permissions. Check under Review >> Protect Workbook to see if the file has been password-protected. If so, you will need the file's password.
As to the format of those cells, if that is the way you got the file (whatever it is), there are very few reasons for such inconsistencies. You see, Excel is as dumb as a box of rocks, but it is CONSISTENTLY that dumb. For Excel, ALL cells are initially formatted by the same rules. If you have formatting inconsistencies, there are very few possible sources of these inconsistencies.
1. The cells were originally formatted that way from their source.
2. The cells were manually, selectively reformatted by column, by row, or by cell.
3. A function is involved - and it is conditional on something that we can't see.
4. Some type of VBA code underlies the worksheet or workbook and is selectively raising havoc. (This is an extension of #3)
5. (VERY rare...) You have a damaged copy of Excel or Office.
Note that based on your .PDF presentation, we cannot look at the spreadsheet to tell which one of those reasons applies. We would need to see at least an excerpt of the actual .XLS or .XLSX file. (Or whatever else it is.)
I type is a .xlsx. I tried uploading the actual .xlsx file and the site doesn't provide attaching the file type. As you stated, Excel is consistent in how it formats cells. The more I've worked on this the more it looks to be coming from the source system file. I've got an engineer looking at the source file schema, as I believe that's where this is possibility happening. I'll keep you posted. Thanks again for the feedback and assistance.